Printing apparatus

ABSTRACT

A continuous screen printing apparatus of the type having an endless screen mounted on spaced parallel cylinders for printing insignia on a flexible web supported on a movable platen adjacent said screen. Means are provided for laterally and longitudinally adjusting the tautness of the screen and for maintaining the screen taut in the area between the rolls.

[ Sept. 17, 1974 United States Patent [1 1 Vasilantone Xwx EH H02 8 9 H1.

t m F B3 7 m 7 0H0 m1 mN S U k Tae AVM R dR Aa, Ph Pkw MMA mm mm n m PIMN U 647,059 12/1950 GreatBritain......................156/229 [22]Filed: Apr. 26, 1972 [21] Appl. N0.: 247,835

Primary Examiner-Clyde 1. Coughenour 52 US. 101/122, 74/24214 R, 118/34,g f g Agent F"mEdward Dyson [57] ABSTRACT A continuous screen printingapparatus of the type having an endless screen mounted on spacedparallel cylinders for printing insignia on a flexible web sup- O 9 Hun7 h mmw ue m 1 MUN O; 1% B "W MR m4 2 m4 5 WS 61 I10 C l m u IFZ 11 1 55[56] References Cited UNITED STATES PATENTS ported on a movable platenadjacent said screen.

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PRINTING APPARATUS This invention relates to a textile printingapparatus for continuously printing textile webs of an indeterminentlength. More particularly this invention relates to Y a stencil screenprinting apparatus employing an endless screen mounted on spacedcylinders and having a screen in printing engagement with a movablewebcarrying platen.

This invention is related to the continuous stencil screen printingapparatus disclosed in my US. Pat. No.

3,468,247, issued Sept. 23, 1969, entitled CONTINU-.

OUS PRINTER WITH MEANS T MAINTAINA MOVING WEB LATERALLY TAUT, and in myUS. Pat. No. 3,688,692, issued Sept. 5, 1972, entitled PRINTINGAPPARATUS.

One of the primary objectives of the invention disclosed in theabove-mentioned US. Pat. No. 3,468,247 is to maintain the web of textilematerial to be printed laterally taut on the moving platen to insureproper registration and optimum printing contact when the web is broughtinto printing engagement with the stencil screen.

It is also desirable to maintain the printing screen laterally taut atall times for optimum and accurate printing contact. It is generally notdifficult to maintain the screen laterally taut and at a uniform widthas it passes over the cylinders, in that the cylinders are provided withannular grooves or other means on the outer edges thereof for grippingthe edge portion of the endless stencil screen for purposes ofmaintaining a uniform width. However, there is a tendency for the screento contract in those areas of the screen that are between the cylindersand are not in contact therewith.

Therefore, it is a principal objective of this invention to providebridging means extending between the cylinders for engaging the sideedge portions and holding taut the endless stencil screen in that areabetween the cylinders.

It is a further objective of this invention to provide cylinders whichare adjustable axially of their lengths such that the lateral tautnessof the screen mounted thereon can be easily adjusted.

It is a further objective of this invention to provide means mountingthe rolls supporting the stencil screen in a manner such that thecylinders can be moved toward each other to facilitate the placement orremoval of the stencil screen.

It is a further objective of this invention to provide a screen printingapparatus whereby the cylinders supporting the screen are adjustableduring operation of the printing apparatus such that where, more thanone screen printing assembly is used in tandem as in multicolor printingoperations, one printing assembly may be readily adjusted relative tothe other to obtain the proper relative registration.

More particularly the objectives of this invention are realized byproviding an apparatus for continuously printing insignia on a movingflexible material, comprising a framework, a moving platen on saidframework for receiving said meterial to be printed, stencil printingmeans on the framework comprising a pair of spaced apart cylindersroatably mounted on axes extending transversely to the direction ofmovement of the platen. An endless tubular screen is mounted over thecylinders and has upper and lower runs at least one of which ismaintained in printing engagement with the platen. The bridge meansextends between the cylinders and engages the side edges of the screento maintain the screen laterally taut in the areas between thecylinders. The cylinders are mounted for movement toward and away fromeach other in a direction parallel to the direction of movement of theplaten for adjusting the longitudinally tautness of the screen and forfacilitating the placement and removal of the screen on the cylinders.The stencil screen has enlarged edge portions on each side thereof, andthe bridge means comprises a pair of elongated rigid members extendingbetween the drums and on each side thereof and having an elongated tracktherein for slidably receiving the enlarged portions-on each side of thestencil screen respectively. Anti-friction means are mounted in thetrack for engaging with the enlarged portions, the antifriction meanspreferably including an endless band of a flexible metal materialextending around rollers rotatably mounted in the track on axesperpendicular to the planeof the platen.

These and other objects of the invention will become more apparent tothose skilled in the art by reference to the following detaileddescription when viewed in light of the accompanying drawings wherein:

FIG. 1 is a diagrammatic illustration of the type of printing system inwhich the screen printing unit of this invention is employed;

FIG. 2 is a perspective view of the screen printing unit of thisinvention;

FIG. 3 is a perspective exploded view of the end assembly of one of thecylinders of the screen printing unit;

FIG. 4 is a view similar to that of FIG. 4 except in elevational crosssection;

FIG. 5 is a perspective exploded view of the bridge means of thisinvention;

FIG. 6 is a perspective view of the bridge means of this invention;

FIG. 7 is a plan view of a detailed segment described as a pop-outdevice;

FIG. 8 is a side view in elevation of the cylinders with the upper andlower bridge means in position;

FIG. 9 is a perspective view showing the relationship of the bridgemeans, retainer ring and printing screen;

FIG. 10 is a partial cross sectional view taken in the area of one ofthe cylinder ends when the cylinder is in the non-expanded position;

FIG. 11 is a view similar to FIG. 10 but is a plan view;

FIG. 12 is a partial cross sectional-view taken in the area of one ofthe cylinder ends when the cylinder is in the expanded position;

FIG. 13 is similar to FIG. 12 but in a plan view;

FIG. 14 is a perspective view of the cylinder support mechanism;

FIG. 15 is a plan view of the cylinder support mechamsm;

FIG. 16 is a perspective view of the cylinder support mechanism in acollapsed condition;

FIG. 17 is an end view of the screen printing unit of this inventionillustrating the cranks used in longitudinally and laterally adjustingthe cylinder ends;

FIG. 18 is a view similar to that of FIG. 14 except that the cylindersare in the collapsed condition.

GENERAL ARRANGEMENT This invention is primarily concerned with theconstruction of the twin cylinder stencil screen printing unit,generally indicated by the numeral in FIG. 2. The twin cylinder screendrive unit is designed to be used in a multiweb printing machinegenerally indicated by the numeral 12 in FIG. 1. A framework 14 supportsa plurality of screen printing units 10 in tandem relationship. Thoughit is not shown or described herein, an ink supply assembly is disposedbetween the cylinders of each of the screen printing units to flood theruns of the screens, both top and bottom, in the areas between thecylinders in a manner well known in the screen printing art. Aparticular ink supply system suitable for use with the screen printingunits of this invention is disclosed in my copending application filedMay 14, 1970, Ser. No, 37,113, entitled PRINTING APPARATUS. Again withreference to FIG. 1, a bottom endless platen 16 is mounted on idler roll18 and driven roll 20 and carries a web 22 to be printed. The web istaken from supply roll 24 and passed through the screen printingapparatus and drier 26, and is accumulated on take up roll 28. Since theprinting screen units are endless and are constantly rotating at speedscorresponding to the platen and the web supported thereon moving throughthe printing apparatus, the units can print on the top runs and lowerruns simultaneously. Accordingly, an upper endless platen is mounted onidler roll 32 and driven roll 34 and carries a web 36 to be printed froma supply reel 38, through the printing machine and adjacent and incontact with the upper runs of the screen printing unit. The web passesthrough a drier 40 at the opposite end of the web printing assembly andis accumulated on a take up roll 42. Support rolls 44 and 46 support thenon-web supporting runs of the endless platen of the bottom and topendless platens respectively. Upper and lower tables 48 and 50 providefirm support on the sides of the printing runs of each platen oppositethe web supporting sides.

The remainder of this specification will be directed to the inventiveaspects of the individual screen printing units. More particularly, thisinvention includes means in each unit for incrementally adjusting thedistance between the two cylinders in each unit thereby longitudinallystretching the printing screen. Further, means are provided for rapidlydrawing the two cylinders closer to each other to permit easy insertionand removal of the endless printing screens. Additionally, means areprovided for axially lengthening the two cylinders uniformly to stretchthe screen in a lateral direction. Finally, means are provided forbridging the area between the two cylinders such that the edges of theprinting screens are, .supported in these areas to maintain the samedegree of lateral tautness achieved when the edges of the screen areactually in engagement with the ends of the respective cylinders.

BRIDGE ARRANGEMENT With reference to FIG. 2, the unit 10 includes a pairof cylinders 50 and 52 mounted on shafts 54 and 56 respectively. Thecylinders rotate relative to the shafts as will be pointed out morefully hereinafter. An endless tubular stencil printing screen 58 isslipped over the cylinders, in the manner shown, for movement in anendless path as the cylinders are rotated. The screen has an upper run60 and a lower run 62.

Referring now to FIGS. 3 and. 4, the end plate assembly of cylinder 50will be described. It is to be understood that the end plate assembly ofcylinder 52 is identical, and the end plate assemblies on the oppositeends of the respective cylinders are identical.

The cylinders are provided with internal reinforcing plates 64 one ofwhich is seen in FIGS. 3 and 4. The reinforcing plates are provided withcentral apertures 66 which receive and center the shaft 54, and thethrust bearing assembly 57 which is fixed to the shaft 54, such that thecylinder rotates while the shaft and hearing assembly remain stationary.An externally threaded sleeve 68 is slidably received over the the shaft54 and has a thrust bearing assembly 70 afiixed to the inner end thereoffor rotatably supporting the inner channel ring 72. The sleeve 68 andthe ring 72 move axially relative to the cylinder 52 for lateraltensioning of the screen printing web as will be more fully describedhereinafter.

. The inner channel ring 72 includes an annular recess 74 which receivesupper and lower pop-out devices 76 and 78 which are affixed to a bridgeretainer ring 80. An outer channel ring 82, having a cylindrical section84 and a flange 86, is secured to the inner channel ring 72 in a mannerto be described below. A web support ring 88 is affixed to the outersurface of the flange 86 of the outer channel ring 82. Fasteners 90 inthe form of threaded fasteners or any other suitable fastener securesthe web support ring to the outer surface of the flange 86 of the outerchannel ring 82, and the channel ring 82 to the inner channel ring 72.The axial edge of the cylindrical portion 84 of the ring 82 abuts theouter surface 92 of the inner channel ring 72 to define an annulargroove 94 therebetween as best seen in FIGS. 10 through 13. The groove94 receives the bridge retainer ring 80.

Wheels 96 are spaced about the inner periphery of the ring 80 and rideon the outer peripheral surface of the cylindrical portion 84 when thecylinder is rotating.

Guide pins 98 permit relative axial movement between the inner channelring 72 and the cylinder 50 while insuring that the channel ring rotateswith the cylinder when the latter is rotated relative to the supportingshaft 54. Since the web support ring 88 and the outer channel ring 82are affixed to the inner channel ring 72 by means of the aforementionedfasteners 90, the cylinder, inner channel, ring, outer channel ring andweb support ring will rotate as a unit relative to the shaft 54. Thebridge support retainer ring 80, however, remains stationary as theother elements rotate with the cylinder. v

The ring 80 is provided with upper and lower bridge locking members 100and 102 which receive bridge locking elements 104 and 106 on bridgingmembers 108 and 110 respectively, as will be described in greater detailbelow.

The web end support ring 88 when affixed to the outer surface of theflange 86 forms a cylindrical supporting surface for receiving aresilient or elastomeric web-lock ring 112. The lock ring 112 has achannel 114 therein snugly receiving an endless locking band 116. Theband 116 is affixed to the side edges of the stencil printing screen 58such that when band 116 is in the channel 114 the screen is locked tothe web-lock ring 112 for movement therewith.

The bridge means will now be described in greater detail. It is to beunderstood that for each twin cylinder unit there are four bridgemembers, a pair on each end for each end'of the cylinders for the topand bottom runs of the stencil printing screen. Each bridge member 108comprises an elongated body of metallic bar stock 118 having a pair ofelongated axially extending slots 120 and 122, one at each end of thebody 118. As seen in FIG. 8, the bridge member is of a length somewhatgreater in distance between the axes of the two cylinders 50 and 52. Aspacer plate 124 of a height generally corresponding to the height ofthe body 1 18 is attached to the mid-portion of the body 118 in the areabetween the inner ends of the slots 120 and 122. Attached to the outersurface of the spacer member 124 is an antifriction band-supporting body126. The ends of the body member 126 are arcuately undercut at 128 and130 respectively generally in conformity to the surface configuration ofthe cylinders. An endless anti-friction band 132 preferably of stainlesssteel or the like is journalled on rollers 134 and 136, which arejoumalled on vertical axes extending generally perpendicular to the axesof the cylinders 50 and 52 and the plane of the platen. Theanti-friction band assembly is positioned within a recess 138 in theupper surface of the body 126. The purpose of the anti-friction band isto generally reduce frictional contact between the web support ring 112and the surfaces of the stationary bridging member. The body 118, spacer124 and anti-friction band-supporting body 126 are shown as being formedof separate pieces joined together by a fastener means 140. It is to beunderstood that these parts could be integrally formed within thelimitations of manufacturing processes.-

The pop-out devices 76 briefly referred to earlier are mounted on theinner surface of the bridge retainer ring 80 such that the bridgeretainer ring is disposed between the bridge member and the pop-outdevices in the area of the slots 120 and 122. The pop-out device 76includes a supporting block 77 having a pivotal mounting 79 on the sidethereof facing the cylinder end for pivotally receiving rollersupporting legs 81 and 83. The pivotal connection 79 includes a pin 85inserted in aligned openings in the support block 77 and in the legs 81and 83. J ournalled to the outer ends of the legs 81 and 83 are rollers87 and 89 respectively. The outer ends of the legs 81 and 83 and,therefore, the rollers 87 and 89, are urged toward each other by aninterposed tension spring 91 spanning the outer ends of the legs 81 and83. The legs tend to assume the position shown in FIG. 7.

Locating pins 93 and 95 extend through the supporting block 77 in adirection toward the bridge retainer ring 80 and as best seen in FIGS.through 13 are received in openings 97 and 99 in the retainer ring. Thelocators 93 and 95 are of such length that they extend beyond the outersurface of the retainer ring 80 and are received in one of the elongatedslots 120 and 122 of the bridge member when the bridge member is inposition spanning the two cylinders 50 and 52. Upper and lower pop-outdevices are provided for each bridge retainer. The relative positions ofthe cylinders, retainer rings and bridge members including the pop-outdevices are clearly shown in FIG. 8.

Referring now to FIGS. 10 through 13, the operation of the pop-outdevices will be described more fully. In FIG. 10, it is to be seen thatthe inner channel 72 and the members attached thereto; namely, the outerchannel ring 82 and the web and support ring 88 are in their innermostposition relative to the cylinder 50. The mechanism for moving theentire assembly toward and away from the cylinder will be described morefully hereinafter as part of the web tensioning system mechanism. In theposition shown in FIG. 10, the stencil printing screen 58 is loose andcan be easily slipped off of the twin cylinders. The edge of the screen58 is bonded to the lock strip 116 which is press-fitted into recess 114in the elastomeric ring 112.

The slot 94 defined by the inner channel rings and the outer ring 82 issubstantially equal to the total thickness of the bridge retainersupport ring .80 and the body and spacer plates I18 and 124 of thebridge member 108. Consequently, when the end ring 82 is moved axiallyoutwardly from thecylinder as indicated in FIG. 12, the bridge member,retainer ring and pop-out device will tend to nest against the outersurface of the end plate 82 by the force from the lateral stretching ofthe stencil printing screen, and, thereby, the force generated by lockstrip 112 acting against the bridging member. In the position shown inFIG. 12, the pop-out device 76 is positioned within the recess 74against the action of the tension spring 91. In the position shown inFIGS. 12 and 13, the anti-friction band support plate is in the samevertical plane as the flange 86 of the outer channel ring 82. However,when the inner channel ring is shifted inwardly, the tension is releasedon the stencil printing screen 82 and the pop-out device forces theretainer ring and the bridging member to the right and also forces thelock strip 112 to the right as shown in FIGS. 10 and 11. In thisposition, the web is loose and can beeasily removed from the twincylinders when they are shifted toward each other.

In the perspective view of FIG. 9, the cylinders are portrayed in theirbroken down position or in that position when their axes are close toeach other to permit the ready replacement or removal of the web. Inthis position, the locking elements 104 of the bridge member 108 arereceived in undercut portions 105 of the locking members 100. Inwardlyof the undercut portions 105, however, is an upstanding ridge 107 whichdefines a trackway with the outer surfaces of the retainer rings 80, forpurposes of receiving the locking elements 104. Therefore, when thecylinders are moved apart, the retainer ring will move therewith and thelocking elements 100 will move relative to the locking elements 104 suchthat the locking elements will be received in the aforementionedtrackway defined by the upstanding ridge 107. This locking arrangementeffectively serves to prevent relative axial movement of between thebridge member and the retainer ring. The elongated slots and 122, andthe pins 93 and 95, effectively prevent relative vertical displacementthe bridge member and the retainer ring. However, the elongated slots120 and 122 pennit the cylinders to be shifted toward and away from eachother with the bridge in position thereon.

The engagement of the lock strip 112 and the antifriction band 132 inthe lock-strip trackway can be clearly seen in FIG. 9. Further, it canbe readily seen, particularly from FIG. 9 how the bridging membermaintains the stencil printing screen laterally taut in the areasbetween the cylinders 50 and 52. When the web is in engagement with andtravels around the cylinder, the upstanding flange 86 maintains thescreen laterally taut. However, prior to this invention, the edges ofthe endless screen tended to draw together in the areas between thecylinders thereby causing a distortion in the printed image.

To insure that the locking strip 112 will not be displaced verticallyand therefore out of engagement with the bridge member, an outer channel142 is attached to the outer surface of the anti-friction band supportand is provided with an overhandling lip 144 which prevents the lockstrip and the attached printing screen edge from shifting upwardly andout of contact with the bridge. The channel 142 does not interfere withthe removal of the screen when the assembly is in the collapsed state.

LATERAL AND LONGITUDINAL TENSIONING MECHANISM The mechanism by which thecylinders are moved toward or away from each other to longitudinallytension the screen printing web, and the mechanism for shifting theinner channel rings and the bridge members supported thereon axially ofthe cylinders to laterally tension the screen printing web, will now bedescribed in detail with reference to FIGS. 14 through 18.

Shafts 54 and 56 are supported by front and rear support frames 200 and202 respectively. Both of the shafts 54 and 56 are suitably keyed in thefront rear support frames to prevent relative rotation. The shaft 54 ismounted for movement toward and away from shaft 56 by means of front andrear trunnion blocks 204 and 210 in the front and rear support frames.The cylinders 50 and 52 are joumalled on front and rear roller thrustbearings 57 and 59. The bearings are suitable keyed to the shafts toprevent relative rotation therebetween. Therefore, as explained earlier,the cylinders rotate relative to the shaft on the bearings. Threadedsleeves 68 are mounted on the shafts 54 and 56 respectively and includethe roller thrust bearings 57 for purposes of supporting the innerchannel rings 72. A complete description of the inner channel ringstructure and the entire cylinder end assembly is set forth earlierherein.

Note that the lateral sleeves 68 are readily received in openings 214 inthe pivoted block assembly 218. The pivoted block assembly 218 comprisesa first section 220 and a second section 222 joined together byinterdigitated fingers 224 and 226 respectively. A threaded lateraladjustment post 228 is threadedly received in internally threadedopenings in fingers 226, while the fingers 224 are provided withelongated slots which permit the two sections 220 and 222 to movetoward. and away from each other as the cylinders are adjusted. Thelateral adjustment post 228 includes an extension actuator rod 230having a crank 232 affixed to the outer end thereof. Note thatlongitudinal fine adjust wheel 266 has an extension post 264 that isrotatably bushed through the first section 250 of the crank and is inturn threaded through the aligner block 251 that is pivotally engaged tothe second section 252.

It can be seen then, that by rotating the crank 232 the entire blockassembly 218 will be caused to move inwardly or outwardly axially of thecylinders by means of the threaded engagement of the lateral adjustmentpost with the block assembly 218. The sleeves 68 as mentioned earlierare threadedly engaged in the block assembly 218 for movement therewith.The sleeves are permitted to slide axially on the shaft 54 and shaft 56;therefore, any axial movement of the block 218 by the turning of crank232 will cause the end assemblies of the cylinders and the bridgemembers supported thereon to move toward and away from the cylinders. Inthis manner the stencil printing screen supported on the ring assembliesand the bridge members will be stretched laterally of the web andaxially of the cylinders. The end assemblies can be aligned with eachother and with the block 218 by threadedly adjusting the sleeves 68.

The longitudinal tensioning mechanism of the web will now be described.Front and rear crank assemblies 240 and 242 receive the front and rearends of shaft 54 and 56. The shafts are keyed against relative rotatingwithin the connector sleeves 246 and in turn with the crank mechanisms.The connector bushings 246 are fixed to section 252 at one end of shaft56 and to drive gears 278 at the other end of shaft 56. Connectorsleeves 245 are fixed to the first section of cranks 250 and arerotatably bushed through trunnions 210 on shafts 54. It is to beunderstood that the rear and front crank assemblies are identical. Eachof the crank assemblies includes a first section and a second section.The first section 250 includes an extension 254 which is slidablyreceived into the pivotal aligner block 251. The aligner block is inturn snugly and pivotally received into the internal portion of thesecond section 252. Extension 254 is provided with an elongated slot 256which allows the actuator extension 230 of the lateral adjust post 228to pass through. The post 228 acts as a pivot for the crank collapseaction as it is rotatably bushed through the walls of the section 252.

The aligner block 251 is held in linear check by the threaded post260-262, adjust extension 264 and wheel 266. The slot 256 of theextension 254 allows for telescopically increasing or decreasing thelengths of the cranks and for adjusting and paralleling the shaft andcylinder respectively.

It can be seen that by turning the cranks 266, the first section 250 ofthe crank assembly will be caused to move toward or away from the secondsection 252 to move the shafts and cylinders toward and away from eachother thereby longitudinally tensioning the stencil printing screensupported on the cylinders. This adjustment can be made while theassembly is printing. it should be noted that the purpose of thelongitudinal adjustment 266 is for infinitely adjusting and locking thespacing and parallel relationship of the shaft and cylinders and for theadjustment of print register. Longitudinal tensioning is accomplishedsimply by turning the crank 266.

The mechanism for rapidly collapsing the cylinders by moving them towardeach other to permit rapid removal or placement of a stencil printingscreen on the cylinders will nowbe explained. This is a twofold systemand the collapsing may be accomplished by the raising or lowering ofonly one of the crank handles since the fixed shaft 56 is rigidlyconnected to both crank mechanisms. A lever 270 is attached to thesecond section 252 of each crank assembly 240. The front and rearsupporting frames each includes shelves 274 supporting reciprocatingracks 276. Rack dirving gears 278 are attached to the ends ofcomplementary connector bushings 246. As the levers 270 of either frontor rear crank assemblies are pulled upwardly the drive gears are bothactuated and are interconnected by the fixed shaft 56. The drive gearsin turn actuate and drive both racks 276 which in turn are meshed withand drive pinion gears 284 at the bottom ends. The pinion gears aremeshed with trunnion racks and to a large extent support the trunnions,which are in partial, slidable engagement with the lower portion ofslots 211. Therefore, as the lever 270 of either crank is pulledupwardly, the second sections 252 of the crank assemblies will berotated around the axis of shafts 56, and the first and second sections250 and 252 will be caused to pivot with respect to each other about apivot point defined by the lateral adjustment post 228. A clearanceopening 199 is provided in the journal support 200 so that the lateralactuator post 230 may seat without interference. FIG. 14 indicates thepost 230 in its seated position. FIG. 18 shows the post 230 pivoted inthe Up position out of seat.l99.

The lever will cause the variable shaft 54 and cylinder thereon to bepulled and drawn toward the fixed shaft 56 and the cylinder thereon.Additionally, the drive gears will rotate as the two sections 252 of thefront and rear crank assemblies are pivoted upwardly and cause the racksto be driven to the left as viewed in FIG. 14. The racks 276 are meshedat their other ends with small pinions 284 which are rotatably mountedon both journal support frames 200-202. The trunnions 210 are caused tomove within the slots 211 toward the other cylinder thereby furtherdrawing the cylinders together. Then, assuming that the lateraladjustment post has been rotated to move the ring assemblies and thebridge members toward the cylinders, the stencil printing screen will beeasily removable from the cylinders. FIGS. 16, 17 and 18 fully depictthe operation of the cranks in collapsing the cylinders toward eachother.

It is desirable for uniform tension and to maintain the individualthreads of the stencil fabric parallel and vertical to each other and tomaintain uniform apertures through the full width and breath of thefabric by achieving lateral and longitudinal tensioning. It is customaryto tension the fabric to an extreme as to arrive at a point where thefabric assumes the character of a rigid plate. This condition provides astable stencil plate with a minimum of flexure, thus overcoming stressesimparted by the applicator and squeegee. This tension condition retainsregister throughout its full surface, aids in release from the printedmatter, and maintains its grip on the supporting cylinders therebygreatly minimizing chances for movement from its frictional contact withits supporting means.

The bridges and their interconnected cylinders are a unitary systemdesigned to achieve from two supporting cylinders a system that is closein function to a single cylinder but yet having all of the advantages ofa multi-cylinder system.

In a general manner, while there has been disclosed effective andefficient embodiments of the invention, it should be well understoodthat the invention is not limited to such embodiments as there might bechanges made in the arrangement, disposition, and form of the partswithout departing from the principle of the present invention ascomprehended within the scope of the accompanying claims.

I claim:

1. An apparatus for continuously printing insignia on a moving flexiblematerial comprising a framework, a moving platen on said framework forreceiving said material to be printed, stencil printing means on saidframework comprising a pair of spaced apart cylinders rotatably mountedon axes extending transversely to the direction of movement of saidplaten, an endless screen mounted over said cylinders and having upperand lower runs one of which is maintained in printing engagement withsaid platen, relatively stationary bridge means extending between andgenerally supported by said cylinders and engaging the side edges ofsaid screen to maintain said screen laterally taut in the area betweensaid cylinders.

2. The apparatus of claim 1 wherein at least one of said cylinders ismounted for movement toward and away from the other of said cylinders ina direction parallel to the direction of movement of said platen forrendering said screen longitudinally taut.

3. The apparatus of claim 2 wherein toggle cranks extend between andjoin said cylinders, said cranks having a first or locked positionwherein said cylinders are held apart a predetermined distance, and asecond or unlocked position whereby said cylinders are drawn closer toeach other.

4. The apparatus of claim 3 and including adjustment means for adjustingthe spacing of said cylinders when said crank is in the first position.

5. The apparatus of claim 1 wherein at least one of said cylinders ismounted for movement toward and away from the other of said cylinders ina direction parallel to the direction of movement of said platen forrendering said screen longitudinally taut.

6. The apparatus of claim 5 wherein said screen has an enlarged edgeportion on each side edge thereof, and said bridge means comprises apair of elongated rigid members extending between said cylinders and oneach side thereof and each having an elongated track therein forslidably receiving said enlarged portions respectively.

7. The apparatus of claim 6 and including antifriction means mounted insaid track for engagement with said enlarged portions.

8. The apparatus of claim 7 wherein said anti-friction means is anendless band extending around rollers rotatably mounted in said track onaxes perpendicular to the plane of said platen.

9. The apparatus of claim 8 wherein said band is of a flexible metal.

10. The apparatus of claim 5 wherein toggle cranks extend between andjoin said cylinders, said cranks having a first or locked positionwherein said cylinders are held apart a predetermined distance and asecond or unlocked position whereby said cylinders are drawn closer toeach other.

11. The apparatus of claim 10 and including adjustment means foradjusting the spacing of said cylinders when said crank is in the firstposition.

12. The apparatus of claim 1 and including lateral adjusting means foraxially extending each of said cylinders and for laterally shifting saidbridge means to adjust the lateral tension on said screen.

1. An apparatus for continuously printing insignia on a moving flexiblematerial comprising a framework, a moving platen on said framework forreceiving said material to be printed, stencil printing means on saidframework comprising a pair of spaced apart cylinders rotatably mountedon axes extending transversely to the direction of movement of saidplaten, an endless screen mounted over said cylinders and having upperand lower runs one of which is maintained in printing engagement withsaid platen, relatively stationary bridge means exteNding between andgenerally supported by said cylinders and engaging the side edges ofsaid screen to maintain said screen laterally taut in the area betweensaid cylinders.
 2. The apparatus of claim 1 wherein at least one of saidcylinders is mounted for movement toward and away from the other of saidcylinders in a direction parallel to the direction of movement of saidplaten for rendering said screen longitudinally taut.
 3. The apparatusof claim 2 wherein toggle cranks extend between and join said cylinders,said cranks having a first or locked position wherein said cylinders areheld apart a predetermined distance, and a second or unlocked positionwhereby said cylinders are drawn closer to each other.
 4. The apparatusof claim 3 and including adjustment means for adjusting the spacing ofsaid cylinders when said crank is in the first position.
 5. Theapparatus of claim 1 wherein at least one of said cylinders is mountedfor movement toward and away from the other of said cylinders in adirection parallel to the direction of movement of said platen forrendering said screen longitudinally taut.
 6. The apparatus of claim 5wherein said screen has an enlarged edge portion on each side edgethereof, and said bridge means comprises a pair of elongated rigidmembers extending between said cylinders and on each side thereof andeach having an elongated track therein for slidably receiving saidenlarged portions respectively.
 7. The apparatus of claim 6 andincluding anti-friction means mounted in said track for engagement withsaid enlarged portions.
 8. The apparatus of claim 7 wherein saidanti-friction means is an endless band extending around rollersrotatably mounted in said track on axes perpendicular to the plane ofsaid platen.
 9. The apparatus of claim 8 wherein said band is of aflexible metal.
 10. The apparatus of claim 5 wherein toggle cranksextend between and join said cylinders, said cranks having a first orlocked position wherein said cylinders are held apart a predetermineddistance and a second or unlocked position whereby said cylinders aredrawn closer to each other.
 11. The apparatus of claim 10 and includingadjustment means for adjusting the spacing of said cylinders when saidcrank is in the first position.
 12. The apparatus of claim 1 andincluding lateral adjusting means for axially extending each of saidcylinders and for laterally shifting said bridge means to adjust thelateral tension on said screen.